> ## Documentation Index
> Fetch the complete documentation index at: https://www.agent37.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Host Claude Code

> Run Anthropic's Claude Code on its own always-on instance, signed in to your own Anthropic account.

The `agent37-claude-code` [template](/docs/agents-api/templates) runs Claude Code, Anthropic's coding agent, on an Agent37 instance: an always-on computer with the same chat API, sessions, files, and URLs as every other template. The image is lean, with no browser and no desktop. Claude Code runs on **your own Anthropic account**: Agent37 never supplies or bills Claude model usage, and there is no managed-model option on this template, so connect your account before the first chat turn.

## Create the instance

One call to the hosting API at `https://api.agent37.com`:

```bash curl theme={null}
curl -X POST https://api.agent37.com/v1/instances \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "template": "agent37-claude-code" }'
```

The `201` response carries the instance id and its URL, `https://{instanceId}.agent37.app`, which routes to the gateway on port `3737`. The terminal is on port `7681` and the file browser on `8080`, each at `https://{instanceId}-{port}.agent37.app`; see [Instance and preview URLs](/docs/agents-api/urls).

## Connect your Claude account

Three ways to connect. Until one of them is done, a chat turn fails with `auth_error`, and `GET /v1/health?agent=claude-code` on the instance URL reports `"healthy": false`.

**Log in from the instance terminal.** Mint a [signed URL](/docs/agents-api/urls#browser-access-with-signed-urls) for the terminal port:

```bash curl theme={null}
curl -X POST https://api.agent37.com/v1/instances/ab12cd34ef/signed-url \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "port": 7681 }'
```

Open the returned `url` in a browser and run `claude auth login` in the shell. The login persists on the instance volume, so it survives restarts and updates.

**Set `CLAUDE_CODE_OAUTH_TOKEN`.** The way to go when your app provisions instances headlessly. Generate the token on your own machine with `claude setup-token`, then pass it as [instance env](/docs/agents-api/instances#environment-variables) on the create call:

```bash curl theme={null}
curl -X POST https://api.agent37.com/v1/instances \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "template": "agent37-claude-code", "env": { "CLAUDE_CODE_OAUTH_TOKEN": "..." } }'
```

**Set `ANTHROPIC_API_KEY`.** Same shape: pass an Anthropic API key as `env` on create instead.

## Send the first message

Chat is the instance URL plus a path, with the same `sk_live_` key sent as the `X-Agent37-Key` header. `claude-code` is the template's default agent, so there is no `agent` field to pass:

```bash curl theme={null}
curl https://ab12cd34ef.agent37.app/v1/responses \
  -H "X-Agent37-Key: sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "input": "Clone github.com/expressjs/express and summarize how routing works." }'
```

Set `"stream": true` to receive the turn as Server-Sent Events instead of one JSON body, and reuse the returned `session_id` to continue the thread. See [Send a message](/docs/agents-api/chat) and [Streaming](/docs/agents-api/streaming).

## Models

`GET /v1/models` on the instance lists five aliases: `default`, `fable`, `opus`, `sonnet`, and `haiku`, all with provider `anthropic`. Pass one as `model` on a turn. Usage bills to your Anthropic account, not your Agent37 wallet. See [Models](/docs/agents-api/models).

## Bring your own model

Claude Code can run on a different model provider entirely: point it at any Anthropic-compatible Messages endpoint with two more `env` entries on the create call. With OpenRouter:

```bash curl theme={null}
curl -X POST https://api.agent37.com/v1/instances \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "template": "agent37-claude-code",
    "env": {
      "ANTHROPIC_BASE_URL": "https://openrouter.ai/api",
      "ANTHROPIC_AUTH_TOKEN": "<your OpenRouter key>"
    }
  }'
```

No Anthropic account is needed: model usage bills the key behind `ANTHROPIC_AUTH_TOKEN`, and health reports healthy once the instance is up. To pin what each [model alias](#models) runs, add role variables as provider slugs: `ANTHROPIC_DEFAULT_SONNET_MODEL`, `ANTHROPIC_DEFAULT_OPUS_MODEL`, `ANTHROPIC_DEFAULT_HAIKU_MODEL`, and `ANTHROPIC_DEFAULT_FABLE_MODEL` (for example `"ANTHROPIC_DEFAULT_OPUS_MODEL": "anthropic/claude-opus-5"`, so a turn with `"model": "opus"` runs that slug). Claude Code is built for Anthropic models; pointing a role at another family can mishandle the tool calls it edits files with.

Runnable version: [claude-code-byo-model](https://github.com/agent37-platform/examples/tree/main/claude-code-byo-model) in the examples repo.

## Connect apps

[App integrations](/docs/agents-api/integrations) work here like on every system template: drive the `/v1/integrations` endpoints to connect your users' Gmail, Slack, Notion, and hundreds of other apps, and the platform registers its Composio MCP server with Claude Code automatically.

## Custom image

To add your own tools, build on the clean base image, which ships Claude Code and the gateway with no managed integrations, the same pattern as `hermes-base`:

```dockerfile theme={null}
FROM ghcr.io/agent37-platform/claude-code-base:latest
```

See [Build a custom image](/docs/agents-api/custom-image).

## Troubleshooting

| Symptom                                                       | Fix                                                                                                                     |
| ------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------- |
| A turn fails with `auth_error`                                | No Claude account is connected yet: connect one of the three ways above.                                                |
| `GET /v1/health?agent=claude-code` reports `"healthy": false` | Same cause: the harness reports unhealthy until an account is connected. `ok: true` alone only means the gateway is up. |